Common Cause is a non-profit, nonpartisan citizen's lobbying organization whose stated purpose is to promote open, honest and accountable government. One of the issues which Common Cause follows closely is campaign financing.
Common Causes' Soft Money Laundromat (http://www.commoncause.org/laundromat) is a searchable database of special interest soft money contributions to the Democratic and Republic national party committees. It shows who got what and 'what it means for our democracy.'